It is well known that organic isocyanates may be polymerized to high molecular weight linear organic polymers. Thus, e.g. in U.S. Pat. No. 2,965,614, a process is described wherein an isocyanate in which the isocyanate group (or groups) is attached to a carbon atom bearing at least two hydrogen atoms is treated under anhydrous conditions with an alkali metal anionic catalyst at a temperature below about -20.degree. C. in a solvent for the isocyanate and the catalyst. The products are described as being linear polymers.
Similarly, in U.S. Pat. No. 3,163,624, trimethylene diisocyanate or alkyl and/or aryl substituted trimethylene diisocyanates are treated with an alkali metal anionic catalyst at a temperature of from about -20.degree. C. to about -100.degree. C. or lower to produce a linear polymer containing 6-membered rings.
In U.S. Pat. No. 3,048,566, a high molecular weight synthetic linear polymer of an organic polyisocyanate having at least two vicinal isocyanate groups is described. The polymer is characterized by a repeating five-membered ring structural unit in which the nitrogen of one of the isocyanate groups is bonded to the carbon atom of an adjacent isocyanate group. The products are made by polymerizing the isocyanate under anhydrous conditions at a temperature below about 75.degree. C. The polymers may be depolymerized by thermal cracking. Example III of this patent describes the polymerization of cyclohexane-1,2-diisocyanate. A similar polymerization process is found in U.S. Pat. No. 3,450,676.
Finally in Corfield and Crawshaw, Chemical Communications, Vol. 4, pages 85-86 (1966), the polymerization of cis 1,3-cyclohexane diisocyanate is described. The process used consists of treating the isocyanate with sodium cyanide in a dimethyl formamide solution at a temperature of from -40.degree. C. to -60.degree. C. The resultant polymer unit is described as ##STR3##